How to configure default state of GPIO ouput

[ampad]

Working with NRF5 SDK 15.0.x, if I configure an GPIO as output, its initial state is low. I can set it high after configuration, but it is briefly low. Is there anyway to configure the initial state to be high/set before the pin is connected as ouput using the SDK?

Thanks

[Fred]

Unless I understand it incorrectly, if you need to be sure that it is high even before you have started your program adn/or do the configuration, I guess you would required a pull-up on the board?

[ampad]

It does have an external pullup, I am configuring the pin in an open drain configuration using NRF_GPIO_PIN_S0D1 as the drive type as follows"

    nrf_gpio_cfg(pin,
        NRF_GPIO_PIN_DIR_OUTPUT,
        NRF_GPIO_PIN_INPUT_DISCONNECT,
        NRF_GPIO_PIN_NOPULL,
        NRF_GPIO_PIN_S0D1,
        NRF_GPIO_PIN_NOSENSE);

When this function is called, the pin is pulled low as the default state for the output pin is cleared. What I am looking for is a way for the value associated with the pin to be set to 1 (i.e. disconnected) at configuration time so that the pin is not pulled low.

[awneil]

You can see the source of nrf_gpio_cfg() - it just writes to the PIN_CNF register.

Check the Product Specification for register descriptions & to see if there's an option to do what you want...

[ampad]

Digging through the code as @awneil suggested, I found that nrf_gpio_pin_set() simply updates the OUTSET register, so the pin does not need to be configured as output first. Calling this before configuring the pin as output results in the behavior I was looking for. 

nrf_gpio_pin_set(pin);
nrf_gpio_cfg(pin,
    NRF_GPIO_PIN_DIR_OUTPUT,
    NRF_GPIO_PIN_INPUT_DISCONNECT,
    NRF_GPIO_PIN_NOPULL,
    NRF_GPIO_PIN_S0D1,
    NRF_GPIO_PIN_NOSENSE);